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Tuesday, December 7, 2010

Viruses don't have lives, don't have cells and without a host. They are just inert packet of chemicals. But viruses aren't exactly dead, either, because they have genes, they reproduce and evolve through natural selection.

Demitry Ivanovsky, a Russian microbiologist reported that an infection in tobacco plants spreads through something smaller than a bacterium called tobacco mosaic virus.

Wendell Stanley, an American biochemist purified tobacco mosaic virus into needle like crystals of protein, winning him a Nobel Prize in 1946 awarded in chemistry, NOT medicine.

Some viruses sneak DNA into a bacterium through a long tube known as a pilus; - considered as its sex appendage :).

Virus comes from a Latin word for "poison" or "slimy liquid", an apt descriptor for bugs that cause flu and the common cold.

Scientists tracking a pneumonia outbreak in 1992 in England found a massive new kind of virus lurking within an amoeba inside a cooling tower, which was so large and complex and they initially assumed it was a bacterium.

The virus is now called "Mimivirus" because it mimics bacteria and it was also partly because Didier Raoult, a French biologist, who helped sequence its genome, fondly recalled his father telling the story of "Mimi" the Amoeba".

Mimivirus has more than 900 genes, which encode proteins that all other viruses manage to do without. Its genome is twice as big as that of any other known virus and bigger than that of many bacteria.

Mamavirus, a close relative of Mimivirus is even bigger also turned up inside an amoeba in a Paris cooling tower. It has its own dependent, a satellite virus named Sputnik.

Amoebas are great places to seek out new viruses as they like to swallow big things and so serve as a kind of mixing bowl where viruses and bacteria can swap genes.

Viruses are already known to infect animals, plants, fungi, protozoa, archaea and bacteria, while Sputnik and Mamavirus can infect other viruses.

Half of all human DNA originally came from viruses, which infected and embedded themselves in our ancestor's eggs and sperm cells.

The virus, dubbed Phoenix, was a dud.

Other viral relics in our genomes may play a role in autoimmune diseases and certain cancers.

Some viral proteins do good, as they may have kept your mother's immune system from attacking you in utero, for instance.

A virus called HTLV, which coevolved with humans for thousands of year, is being used to uncover prehistoric migration patterns. Its modern distribution suggests that Japanese sailors were the first people to reach the Americas, millenia before Siberians wandered across the Bering Strait.

Scientists suspect that a large DNA-based virus took up residence inside a bacterial cell more than a billion years ago to create the first cell nucleus. If so, then we are all descended from viruses!

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